I need to start by saying I had a really hard time warming up to Cinders herself at first. She's not your typical proactive fantasy heroine. She's passive, reactive, and honestly kind of miserable, which can be grating.
But after thinking about it, that's the whole point. Her drive isn't to slay a dragon or claim a throne. It's pure, desperate survival in a household where she's treated as a live-in servant by her stepmother and stepsisters. Every decision she makes, every bit of cunning or resourcefulness she shows, stems from that basic need to get through the day without being crushed. It's a quieter, sadder kind of motivation, but it makes her eventual moments of rebellion—like going to the ball—feel earned, not heroic.